If the class has no method 'bufferEmpty()' then it's likely the driver IC has no buffer, or the buffer is handled differently than with the other chip.
What is your level of understanding code? Display hardware? This is not a beginner task. You have to really understand the difference in driver hardware/software in order to adapt the other program for this use.
Is there not an Adafruit example sketch for this display that you can consult?